This invention relates to devices for protection from electric shock and more particularly to devices which guard against electric shock from live conductors supported by utility poles.
In the electrical power distribution field cylindrical insulators known as fixed post insulators are mounted to vertical wooden poles and carry electrically energized, non insulated, cable conductors. The insulators and conductors are often mounted at different angles to the pole depending on how the conductor is to be carried by the pole and its relationship to other conductors carried by the pole. Many times a plurality of conductors are carried on a single pole, each conductor being supported by an individual, cylindrical, fixed post insulator. A typical arrangement would comprise two opposing insulators mounted near the top of the pole and at right angles to the pole with a third insulator mounted along the vertical axis of the pole at the top of the pole. Each insulator would carry a live conductor, each conductor being in parallel relation to the others. Another typical arrangement would comprise two insulators mounted to the pole at less than right angles and inclined upward. Each would carry an energized conductor. Also, insulators are often hung from horizontal arms of a vertical pole with the conductor carried at the bottom of the insulator. These are known as suspension insulators. This arrangement allows the insulator and conductor flexibility independent of the pole in high velocity winds.
When repair work is required to be done on the pole or on the insulators or conductor cable near the pole, a means for preventing electrical shock to repair personnel from the live conductors is needed. In the past, elongated conductor guards, called line guards, have been used to cover the conductor up to the point of the conductor's connection to the insulator post. If the lineman is using only the elongated conductor guards, a section of live conductor is left exposed at the insulator. This leaves a risk of electric shock to the lineman who is working at or near the area of the fixed post insulator.
Insulator covers have been devised which will cover the conductor at the area of its connection to the insulator. These have primarily been of the type which will fit over the insulator post and will allow a line guard to overlap it at each end to provide a continuous area of protection around the area of the insulator. Many of these insulator covers can be used to cover either a vertical or a horizontal fixed post insultor.
Most conductors are made of elongated wire cable which has a certain degree of flexibility. This flexibility is desirable as it allows the cable to flex in a strong wind, preventing damage to the utility poles. However, this flexibility also allows the cable to sag somewhat towards the ground. A standard line guard, even when it overlaps a traditional insulator guard is often not secured to a fixed point, but can slip or "follow the sag" of the cable. This slippage could unexpectedly expose a section of live conductor to the lineman working on a cable. Standard insulator covers do not have the flexibility to accommodate a sagging conductor and will not mate well with a line guard placed over a sagging conductor. Thus, the junction between the line guard and the insulator cover may be broken unexpectedly, exposing a live section of the conductor to repair personnel.
Standard insulator guards are not secured to either the pole, insulator or conductor. They are merely placed over the insulator and conductor and are held in place by gravity. Since the insulator guard is not secured to the insulator or conductor, it may be accidentally removed or jostled out of place by repair personnel causing an unexpected electrical hazard. Also, the insulator must be mounted to the pole at such an angle that gravity will not cause it to slip off.
Utility poles and their conductors usually are routed along roadways. Many times there are curves or turns in the road, which the poles and conductors follow. Thus, a conductor may not always be routed linearly. The conductor may be routed from one utility pole to another which is not in a direct line with the previous poles, causing the conductor to form an angle or curve from the previously routed conductor. Traditional insulator covers are generally rigid and are not able to adapt to curves in the conductor. Thus, they will not mate well with a line guard placed over a conductor that curves or angles from the pole. In such cases there is a greater risk of accidentially exposing a section of live conductor at the point where the insulator guard and the line guard mate.
When repair work needs to be done on a suspension type insulator, standard insulator covers will not be acceptable since they will not be able to be inverted and placed over the insulator. Through gravity they will fall off of the insulator or will have to be secured to the insulator by some other means.
Thus, there is a need in the field for an insulator guard which will cover a fixed post insulator or a suspension type insulator without regard to the angle of the insulator to the utility pole. Also, there is a need for an insulator guard which will mate with a standard line guard to insure an uninterrupted, insulated work area for repair personnel. Further, there is a need for an insulator cover which will accommodate a sagging or curved conductor and which will form a secure junction with a standard line guard placed over the sagging or curved conductor. Also, there is a need for an insulator guard which can be secured in position over the insulator and conductor (whether it be of the fixed post type or the suspension type) to prevent the cover from being accidentally removed from the insulator or from slipping off of the insulator to provide a safer, more risk free working area near the fixed post insulator.